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Patented Apr. 3, 1951 astute PRESSURE PROVIDING DEVICE Pages. Michigan aim-1m as'signor to 303* Manufacturing Company, a corporation of Original; application April 9, 1943, Serial No. ds-2 ,42 2. V Divided and this application Novem ber 23, I9 I4','SeriaI No. 564,854

M invention relates to air compressors, and

more particularly to muiti s'ta'ge air compressors which are especially adapted to", but in no sense limitecl to; use in cabin pressurizing' systems of aircraft.

-15 Claims (Cl. 230 -26) in the operation of aircraft at high altitudes centrifugal type superchargers, and it is further desirabie, iii view of fiigl'it at different altitudes, to provide for multistage operation under some circumstances but to beahle' to dispense-with this under conditions offiig'ht' at lo'vver altitudes; It is further desirable to provide for the automatic contro'i' of the shift from one mode of operation to another under control of mechanism" responsive" to ambient pressures. It is still further desir'ahle to make rovision for the unloading of thefirst Stage of amult'hstage compressor and to make previsiofl tor permitting the second stage selectively to take fluid from the samesource's fr which the first stage takes fluid or from the di charge of the first stage, aridto providecon .7 mg me ns for" the suitable governing of the u fildadirig device and of the means for changing the point fromwhich the second stage takes fluid;

It is anobject of my invention to rovide an improved cabin pressurizing' pressure providing device; It is" another object of my invention to provide im roved multi-s'tage cabin pressuriz irrg device. Itj's' a further object or m invention to provide an improved gaseous fluid compressor. Itis still another object of my invention to prjo vid'e" plural stage supercharging device" in which regulationof th iiit'ake pressure of the second stage is eifected' by means of a-hypas's vai e variably distributing air fio'hi the fiist-Stage' discharge :between th second sta ei ritals and line to the atmosphere, said vaive being governed automatically by the rateor new from the second Stitg discharge. If; is; S'ti-ll another objeet of my invei 'tio'ri tapas vise ariimproved rh-ulti-stage" supercharger havi-iig' intakes of 'ty of stages so related and controlledigh pressure stage may readily" have its intake connected Withth s' ce of supply orair to the intake: of the lowerpr'essurestage or with the discharge of the lower pressure stage. It" is yet a furtherobject of my invention to p'r'civide an improvedplural stage compressor having an: unloading device associated with its first stage arid valve 'means associated with its second stage for selectively connecting the intake ofthe P latter stagewith the: same source-iron: which the stage takes fluid orwvitn" the discharge of the stage, and having altitude responsive me ns for controlling the unloading device and the valve means. It is still another object of the inven tion to rovide a plural stage rotary com ressor having valve means associated with the intake of its second stage permitting selective connection of said intake either' with the source of supply of air? to the intake of the first stage or with the discharge or the first Stage, and altitude responsive means for controlling said valve means. Otherobjects'and advantages of the in- Vention will hereinafter more fully appear.

'In the accompanying drawings, in which for purposes of illustration one embodiment of my invention is shown together with a fragmentary showing of a portion of a system with which the invention finds advantageous use,

Fig. l" is a generally diagrammatic view showing the mu1ti-stage supercharger in elevation, said supercharger constructed in accordance with the illustrative embodiment of the invention, and aportion of the system for cabin pressurizing to the extent necessary to show the flow of air with respect to the supercharger.

Fig. 2 is a fragmentary sectional View showing the operating mechanism for the valve device which varies the connection of the intake to the high pressure stage with respect to the source from which it takes air.

Fig. 3 is a side elevational View of the improved militi -stage supercharger. v

Fig. 4 is an end elevatiohal vieWof the driving end of the supercharger shown in Fig. 3'.

Fig. 5 is an end elevatiohal view sho'wing'the opposite end of the supercharger shown in Fig. 3.

Fig. 6 isan enlarged, partial. central longitudinal vertical section on the plane of the line 5-6 of Fig. 4-; showing the low pressure stage of the supercharger of Fig. 3 and the drive for said supercharger and a portion of the high pressure" stage. 7 I

Fig. '7 is a View on the same plane as Fig. 6, showing the remainder of the high pressure end .1 of the supercharger portions" d-f the control Fig. 9 is an enlarged horizontal section on the plane of the line 99 of Fig. 3, showing details of the unloading mechanism associated with the low pressure stage of said supercharger, and of a valve device associated with the high pressure stage or" said supercharger, which high pressure stage is shown fragmentarily in Fig. 9.

Fig. 10 is a detail sectional view through the unloading mechanism of the low pressure stage of the supercharger taken on the plane of line iii-19 of Fig. 9.

Fig. 11 is an enlarged fragmentary horizontal sectional view on the plane of the line i l-i l of Fig. 3, showing details of construction of the control device spacially associated with the high pressure end of the supercharger, and particularly illustrating controls utilized in governing the operation of the unloading device for the low pressure stage.

Fig. 12 is a fragmentary sectional view showing the timing gears associated with the high pressurestage of the supercharger, the section being taken on the plane of the line l2-l2 of Fig. 7.

Fig. 13 is a transverse vertical section on the plane of the line l3l3 of Fig. 6.

Fig. ll is an enlarged horizontal sectional view through portions of the control mechanism at the right hand end of the supercharger, the view being taken on the same plane as Fig. 11. Fig. 15- .is a fragmentary vertical transverse section on the plane of the line IE i5 of Fig. 14, showing a manually operable control valve positionable to vary the speed of drive of the supercharger.

Fig. 16 is a section on the planes of the lines iii-16 of Fig. 15.

Fig. 17 is an enlarged detail sectional view on the axis of the speed responsive device for controlling the speed of drive of the supercharger.

Fig. 18 is a transverse vertical sectional view on. the piane of the line l8|8 of Fig. 17.

Fig. 19 is a fragmentary view, generally similar to Fig. 17 but with parts shown in elevation, and illustrating a different position of the parts.

. Fig. 20 is a detail longitudinal sectional view on the plane of the line 2il2fi of Fig. 18.

Fig. 21 is a fragmentary detail view showing a locking screw for the governor.

Fig. 22 is an enlarged horizontal sectional view on the same plane as Fig. 14, showing details of construction of the external-pressurerespcnsive nnloader-valve-controlling pilot mechanism.

Fig. 23 is a fragmentary view on the same plane as Fig. 22, showing the parts in different relative positions.

.Fig. 24 is an enlarged transverse vertical sectioiron the plane of the line 2 1-24 of Fig. 7.

Fig. 25 is a longitudinal View on the line 25-415 of Fig. 24. V

Fig. 26 is an enlarged fragmentary sectional view on the plane of Fig. 6, showing details or the speed controlling drive clutch.

Fig. 27 is a vertical sectional view on the plane of the line 21-2! of. Fig. 6, showing a portion of the driving gearing.

Fig. 28 is an enlarged transverse fragmentary sectional view showing a detail of the drive mechanism.

Fig. 29 is a fragmentary section on the plane of the line 2il29 of Fig. 28, showing a detail of a roller ratchet.

Fig. 30 is a section on the line 3=33:l of Fig. 28, showing another detail of the roller ratchet.

Fig. 31 is a vertical section on the plane of the 4 line tit-3i of Fig. 6, showing the passage arrangement at the intake end of the low pressure stage of the supercharger.

Fig. 32 is a vertical section on the plane of the line 32 32 of Fig. 6, showing the passage arrangement at the intake end of the high pressure stage of the supercharger.

Fig. 33 is a vertical section on the plane of V the line 3333 of Fig. 6, showing the passage arrangement at the discharge end of the low pressure stage of the supercharger.

.Fig. 34: is a vertical section on the plane or" the line3434 of 'Fig. '7, showing the passage arrangement at the discharge end of the high pressure stage of the supercharger.

Referring first to Fig. 1, it will be observed that a rammed inlet lill arranged, for example, at the lead edge of an aircraft wing (not shown) communicates through a passage I92 with the branch conduits [G3 and I94. With the latter conduit We shall have no further concern in this application. The conduit 83 communicates, as shown herein (see Fig. 9), with a fitting H35 which has an opening act communicating with the intake space It? of the first or primary stage its of a multi-stage supercharger, herein generally designated Hi9. The fitting H35 also has formed integral therewith a valve receiving portion 5 l i within a bore i 12 of which a valve H3 is rotatably mounted. This valve H3 has a right angle passage its therein and is adapted in different positions thereof to connect the opening H5, at the opposite end of the fitting its from the conduit I33, with the intake i it of the second stage 1!! of the multi-stage supercharger [39.

In a different position'of the valve H3 (turned 90 clockwise from the position of 9) the passage ii i of said valve connects the space within the fitting I95, at the end of the latter connected'to the conduit 83, directly with the intake it to the second stage II? ofthe supercharger.

The low pressure or primary stage H38 of the supercharger H39 will be described in more detail later, but it may benoted that this. stage is provided with an unloading valve 29 which is governed by external pressures (pressures external to the aircraft) by means later to be described, and that a connection 52! from the outlet side of the unloading valve lfiil ccmmunicates at 22 with a conduit I23, which is connected with and leads from the main discharge opening I2 3 of the low pressure stage Hi8 and constitutes a .discharge line for the latter. The conduit I23 leads to a valve casing I25 in which there is rotatably mounted a valve E26 which distributes the flow of air from the conduit i225 to one or the other, or in part to each, of spaces 12! and 528.

The space I28 is connected with the intake or left hand end of the outer course of a heat exchanger 239, herein shown as of a conventional shell, tube andbaiiie type. The other or discharge end of the heat exchanger sac connects at 18! to V a fitting 133 Whose interior space I35, is connected connected at its left'hand end by a passage {49,

amass with-the interior space MI ofsthe airplane cabin 1-4-2." The other end of the'inner .course of" heat; exchanger I38 is connected, as at I 53, to-a valve casing use in which there: is rotatably mounted a valve member Iii; which is adapted to connect the connection H35, and, adiametrically opposite connection I46 associated with another heatexchanger I H selectively witha conduit M3- or a conduitMQ, the last two'conduits being diametricallyopposite each other? with respect to the valve casing. Hi4, and. the conduit I48 constituting; a portion. of the discharge conduit or line for the second stage II? of: the supercharger; and; the conduit Hi9 being connected to the discharge volute. 555' of a suitably motor driven air circulatorI5Iv arranged. within the cabin space: MI. The conduit I48 isconnected by means of a conduit I53 containing a venturi I54, with the dis-- charge from the-second stage of: the" supercharger The space I34 is connectiblei with. an 'atmos.- pheric vent [.55 through an automatically controlled vent-governing valve. device use- This valve device. comprises a casing. I51 in which a. substantially balanced valve. I58. is reciprocable. A valve stem I59 connects the valve with a diaphragm I66. which divides a chamber-forming housing I8! into two spaces 16 2 and I63. The space E53: is. at the side of the diaphragm it!) towards the valve ififl and is corinectedby a. conduit I64 with. the end of the venturi' towards the supercharger high. pressure. stage discharge, i. e.- theentran'ce or inlet end of the vent/uric The chamber Iii-2 is connected by a conduit tail. with the throat of the venturi, A suitable spring Ifil acts upon the upper side of. the diaphragm to bias the valve I58 towards closed position. When the mass flow-of air through the venturi is large, the pressure differential at opp'ositesidesof the diaphragm IE0 is such as to open the valve I58- and vent-more air to the atmosphere. Whenthe mass flow is: less, the pressure differential falls and the valve I58 closes to a greaterextent. Thus this valve tends to maintain a: relatively uniform has, as shown in Fig. 2, an arm I'll fixed thereto,

and the. arm carries a rounded head il2-received in a slot H3 formed in a piston Il lwhich is e; aircraft to a preselected? level; a portion oi: the hydraulic pressurethen established will be delivered through a port I'Iii into the bore I of the cylinder I75, and this pressure will act upon the piston I14 and move the valve II3. to the position shown in Fig; 9.

The specific structure of the supercharger I99 may now be described, but it will be understood that superchargers of other types may be er'n' played, and also different superchargers-oithe intermeshing rotor type, as for example those having rotors'with lobes and grooves of the gem eratedsuriace type. New referring. to. the figures relating more particularly to the disclosure. of the supercharger, it. will be noted that I have shown, as highly efiicient for use in a systemof character. which has. been so far described briefly, and as especially adapted to the accomplishment ofthe objects of my invention, the supercharger. its. as consisting, in each stage thereof, of a pair of coasting rotors having spe-= cial lobe an'clgroove forms later described. As previously noted; this. supercharger comprises the low pressurestage Hi8 and the high pressure" stage Hi, and the" supercharger also comprises a casing I81. This casing. is. divided into a high pressure section and a low pressure section by a partition, E82, which comprises a relatively thin portion 58-5,.where the sides of the partitionare recessed to provide intake grooves, and a: thicker portion 58%, where the full width of the partition desired in order that space packings may be provided at the ends of the rotors. The casing has an internal enlargement at I at the intake end of the low pressure stage and a somewhat similar internal enlargement, as at I86, for the highpressure stage. These enlargements provide intake: spaces of more convenient form. The

- partition I82 is. traversed by two bores I87 which.

reciprocable. in a cylinder H5. This cylinder is suitably mounted upon any suitable support Il a adjacent the valve casing I I 'I, herein upon apo-r 7 tion of the casing of the supercharger W9; A

spring Ill normally tends to maintain the piston H4 in a position at the left hand end of its cy1inder I15 in Fig. 2, and the arm III in a position at right angles to the positionshown Fig. 2

Accordingly, the valve H3 will normally beheld in a position at 90- clockwise from theposition shown in Fig. 9, unless the piston l'M is moved by fluid to the position shown in Fig- 2;

When the control for the. valve I29 is described,

ment. to" state that upon the-attainment. of' the.

iii)

provide seals for a pair of rotor shafts I88 and lfiir respectively. Each of these rotor shafts. as above noted, carries a pair of rotors. A low pressureor first stage rotor !98 having peripheral lobes lei is mounted on the shaft I88 nearer the driven. end of the latter. A coasting, peripherally grooved rotor I92 having grooves I53 to c'oactl with and receive the lobes I91 is mounted on the corresponding end of the shaft E33; These rotors held in anysuitable manner to their respective shafts, andthey are of such lengths as substantiallycompletely tofill the space from the wider portion of the intermediate partition I82 to the chamber endplate I95 which is formed integral with a housing member I95 containing portions of the driving mechanism. For a sub-' stantial portion. of its interior the walls of the casing iii are a close, space-packing fit, as at 3%, for the first stage rotors; the casing, where this. space packing relation with the rotors is maintained, being generally of the form result ing. from the overlapping, for a relatively small portion of their circumferences, of two cylinders. Other, high. pressure stage rotors I5? and I98? are arranged near the opposite ends of'the shafts: E83 and 889, the lobed rotor I9? which has lobes; I93 upon it being arranged on the shaft I38 and the. grooved rotor I93 having grooves 289 being arranged on the shaft I89, the length of the rotors as? and I85. beingv such as substantially completely to fill the space between the partition I32 andan end plate 2M, which is herein shown; as formed integral with a housing element 2H2- of a composite head at the opposite end of the is! from the driving mechanism; housing. lobes" and grooves.arezhelic'ally dis-- posed, and the rotors each have herein four lobes in the case of the lobed rotors and herein six groove in the case of the grooved rotors. The lobes and grooves are herein shown as shaped at the leading sides thereof with substantially arcuate surfaces while the receding sides correspond to generated surfaces, these generated surfaces on the lobes generated by edges on the grooved rotors, and these generated surfaces on the grooved rotors generated by the outermost edge lines of the lobes on the other rotors. The helices of the lobes and grooves are of opposite hand in the different stages and the high pressure stage has its spiral angle smaller than the spiral angle of the low pressure rotors in the construction illustrated, so that the overall length of the high pressure rotors isv somewhat less. Moreover, as will be apparent from Figs. 31, 32, 33 and 34, while the arcuate extent of the intake passages 203 and 284 of the low and high pressure stages respectively is essentially the same, the angular extent of the discharge opening 2&5 of the low pressure stage is substantially greater than the angular extent of the high pres sure discharge opening 206, so that there is an additional feature contributing to the obtaining of substantially the same range of compression in the two stages, notwithstanding that one stage is longer, lengthwise of the supercharger, than the other.

As previously explained, rotors having their lobes and grooves formed with generated surfaces in a well known manner may be substituted for the rotors described, without departing from the invention in its broader aspects in any way. The rotors shown are designed to operate with space packing with respect to each other as well as with respect to the casing; and, because of" the length of the shafts E88 and I89, pairs of tim ng gears are provided'near each end of the shafts, the timing gears at the driving end of the shafts being numbered 2%! and 288, these timing gears fixed to the shafts with which they are coaxial. The shaft Hi8 has a stub shaft 2 at its driving end. The space packing between thehigh pressure stage rotors l9? and [98 is maintained by rigidly fixing the high pressure (discharge) ends oi these rotors to sleeves 2l3 and Ziwhich carry timing gears 299 and Zlll.

The sleeve 2l3'is rigidly connected to the shaft i853, as by pins ZIS which connect the lobed rotor to the sleeve 2E3.

The extent of the intake port 263, from the functional aspect, is, with the proportion shown, such that the trailing edges of the grooves 193 and the spaces between the lobes lei pass out of register with the intake port just before engagement'er the start of compression within the tooth grooves and spaces begins. However, if a small amount of overlapping, so to speak, were to be desired, this would be permissible in view of the dynamic effect of the incoming air, which is s cient to of set the tendency towards the reversal of flow caused by the'initial compression.

The which is sealed in the successive progressively diminishing chambers between the rotors and the casing walls is; substantially pressed when the valve E23 is closed and there is no escape or discharge from the pockets in rotors between the time when pairs of tooth spaces or grooves more out of communication with'the intake and the instant that the leading edges of the cooperating spaces and grooves come into communication with the discharge necessarily, approximately the same.

I24. However, the valve l2!) is so positioned, and a port 216 which this valve controls is so positioned, that, with the proportions heretofore explained, tooth pockets whose trailing edges are just ceasing to communicate with the intake are just about to commence to have their forward edges pass the edges of the opening 2 l6 and establish communication with the latter; and as the trailing edges or tooth pockets approach theirpoints of final communication with the opening 216, when the latter is open, they have their leading edges pass beyond the edge of the final discharge opening, whereby there is displacement, but not compression in sealed pockets, of fluid when the openingile is not closed by the valve !2fl.. When the valve I20 is closed, the ratio of compression in the two stages of the compressor is desirably, but not Ratios of compression in each stage of between two and three to one are satisfactory for conditions often encountered; but in no sense should these values be regarded as limiting. For purposes of reference, the discharge lid for the low pressure stage may be considered as an intermediate discharge for. the supercharger while the discharge 553 for the high pressure stage may be considered as a terminal discharge.

The supercharger may be driven in any suitable manner, as by a shaft 2 is which may desirably be driven through a flexible non-backlash drive such as, for example, is disclosed in my application Serial No. 443,414, filed May 18, 1942,

now abandoned; and this shaft He is arranged in alinement with the rotor shaft I89 and-is adapted to be connected to drive the latter by means of a drive shaft 229 with which it has a splined driving connection, as shown at ,22l. The drive shaft 225 is journaled in a ball bearing 222 carried by a plural-part head 223 sup ported by andfixed to the housing W5. Surrounding a cylindrical hub portion 224 of the gear 268 is a bearing sleeve 225, and a cylindrical portion 226 at the right hand end of the drive shaft 228 rotatably surrounds the bearing sleeve and is journaled, thereon- Keyed to the drive shaft is a member 22! having a number of .recesses 228 formed therein receiving rollers 225 adapted, under propercircurnstances, to clutch the member 22? to-a cylindrically bored liner ring 23! keyed, as at 232, to the gear 238. The recesses 228 have relatively: straight base surfaces 235 and radial surfaces 23%. Through the latter surfaces project spring pressed plungers 237 adapted to act upon the rollers 229, and cause them to connect the members 22? and 23! on predetermined relative rotation between the latter members. Springs 238 act against cross pins 235 and move the plungers 231 against the rollers 229. lhe pins are. supported in endclosure plate members 242 and 243, and the rollers have stems 244 loosely received in openings 2&5 in the plates 242 and 243. Theplates 2:22 and 243 are supported to turn with the member 221. It will be noted, referring to Figs. 27 and 28, that if the member 22? be driven counter clockwise, it will be connected by the rollers 229 to the liner ring 23% and, through the latter, drive the gearjBB; and, by virtue of the corn nection of the gear 298 to the shaft 589, drive the rotor use, while, through the meshing of gear 208 with. gear 237 and the mounting of gear 227 on shaft E88, the rotor 96 will also be driven. .If the gear "268 be driven counterclockwise at a, greater angular rate than themember 227 it will "not "be connected to that member but may turn freely in the direction mentioned relative to it.

- The shaft I88 has another shaftZ I1 connected with it. it will be noted that the shaft 2! I is connected by means of a splined connector element 2&8 with the shaft I88. This connector element i hollow from end to end, as at 249. The lefthand end of the shaft 2 I I, as Viewed in Fig. 6,- is journaled in' a ball bearing 25! carried by the pluraLpart head 223 and carries a gear 252 somewhat smaller than the gear 221. A gear 253, somewhat larger than the gear 208, meshes with the ear 252 and is journaled by a ball bearing 255 on a cylindrical portion 255 of the drive shaft 228. The gear 253 also has a sleeve portion-251 internally splined at 258 and supported by a ball bearing 259 on a further cylindrical portion 26!! of the drive shaft 228. Discs 2621connected to the sleeve portion 25? are interleaved with other discs 263 connected by splinesfle' to the drive shaft 229 which has a flange 265'adjacent the bearingj'ZEB serving as an abutment forthe end one of the interleaved series of discs .262 and'253 when these are pressed together to connect the gear 253 to the drive shaft 22s. A follower mem ber 26'l',as shown in Fig. 26, is slidably'supported on a packing ring 266 mounted on the shaft 220, and has an annular outer sleeve portion 265 with whose bore a peripherally packed plate 27b acts to form a chamber 2H forthe clutch applying hydraulic pressure. A ring 212 seated in an internal groove in the sleeve portion 269 provides 10 I I thatit is always partially submerged, and so that its intake is always submergedfin the horizontal position of the casing, in the 'oil the sump. Thispump, as shown "in .Figf24, includes a casing 283 having intersecting rotor chambers 2B4 therein in which are rotors 285 having intermeshing teeth 28% arranged at a slight angle to elements of .a cylindrical "surface in which the outermost points in the rotor teeth lie. An intake passage 28! conducts oil to the lower sides of the rotors 285, and this oil is carried around by the teeth 2'86 and is discharged to a discharge space 288 above the plane of the mesh line of the rotors 235. One of the rotors drives the other, and the first mentioned rotor is provided with a shaft 289, Fig. 7, which'is driven through a an abutment for a flexed annular spring 213 7 whose opposite side presses upon the side of the plate 218, and the spring 2'53 normally maintains the follower member 267 in clutch unloading position.

When the clutch is loaded the gear 253 will be connected directly to the shaft 228 and will'drive the gear 252 and so the gears 207 and2ll8', and thus therotors' 'I 98 and IE2; and because the gear 2598. will 'then be rotated faster than the member 1221 and in the same direction with the latter, there will simply be an overruning clutch action and no tendency for connection between gear 20.8 and member 227.

When the drive shaft 22! is rotated counterclockwise in Fig. 4 and the female rotors I92 and I98 turn in the corresponding direction while the male rotors turn in the opposite direction, air taken in through the intake connection to the low pressure stage will be entrapped between the casing and the rotors and be progressively moved, and, if it remains entrapped, be compressed as it is moved to the discharge connection-12d, while air entering the high pressure rotors through the intake IIB will also be oompressed as it is moved, in the opposite direction longitudinallyof the shafts I88 and I89, to the discharge connection for the high pressure'stage. Hydraulic means having a common operating fluid-are provided respectively for eiie'cting an automatic change in the driving rate of the rotors upon predetermined changes in the speed of operation of the supercharger and for controlling the position of the valve i2i upon predetermined changes in external pressure.

The base of the casing Iili contains a sump zse between the lower wall of the rotor housing and an outer wall 285 forming an integral part of the casing 23-2. The sump 23%} includes a portion 2853 in the plural-part head 262 and is normally horizontal when the supercharger is horizontal. A 121111111282 is positioned in the chamber 280 so train of gearing including a pinion 290 on the shaft I89, a gear 29I driven by the pinion 29B and driving a second pinion 292 herein shown as formed integral with and coaxial with the gear 29!, the latter pinion engaging and driving a gear-293 secured to the shaft 289. The discharge passage 283 communicates with a passage 295 openinginto a bore 296 in a sleeve member 29] and passes through a strainer device 298, and from the latter by way of an annular passage 299 to a vertically extending passage 300 in the element 3M of the composite head 3B2. Passage 30!) opens into an annular groove 303 whose opposite side opens into a passage 3%, whose upper end opens into a chamber 305. This chamber constitutes a distribution point for oil for lubricating purposes and for operating the speedchanging clutch mechanism previously described, and also for fluid for closing the valve I20. In line with the passage 324 there is another passage BQG opening upwardly from the chamber 395. This communicates with an annular groove 301', in a bushin 3E8 surrounding the shaft I88. This annular groove has continuously incommunication with it obliquely disposed passages 3539 opening into a chamber 3 I!) which communicates with the hollow interior of the shaft I88 which delivers lubricant to and through the bore 249 of the connecting element 248 into the stub shaft 2H and through the latter into a chamber 3i 3 formed in a head member 312 at the extreme left hand end of the supercharger as viewed in Figs. 6 and 7, from whence it is delivered through a suitable lubricant tube 313 to lubricate the gear couple previously described. After it is discharged over these gears, the lubricant passes downwardly into a chamber 3% and is 0011-. ducted out of the casing back into the sump'280. As the lubricating arrangements for the driving gearing form no part of the subject matter specifically claimed in this application and correspond closely to those described in my copending application Serial No. 458,641, now Patent No. 2,477,003, July 26, 1949, furtherdescription at this point is unnecessary. The chamber 319 in the shaft I88 is separated by a partition 3l5 from a valve receiving bore BIS. Passages 317, Fig. 17, connect the annular groove 32] with the bore 316 at points near the partition 315; and a further annular passage 3H3, formed in the bushing 3118, is connected with the interior of the bore 316 by radial passages 312. The extreme right hand and of the shaft I38 supports a speed responsive governor 329 which serves, in conjunction with a spring 32,! housed in the interior of. a valve member 322, to vary the position of that valve member in the bore 316. This valve member is open from end to end, and the spring normally 1' acts to thrust said valve towards the right in groove 32% adapted, in theposition of .thevalve shown in Fig. 17 to connect the passages 3 I! and 3l9, and in the position shown in Fig. 19 simply topreventany discharge .of fluid through the passages 3H. It has another and longer groove 325 which, in the position of Fig. 17, performs no function, but in the position of Fig. 19 connects the passages 3E9, through a slight annular enlargement 326 of the valve chamber, and ports 32! in the governor mounting, to a chamber 328 which communicates with the sump 289.

The governor includes fly weights 329 pivotally supported on transverse pins 330 in earlike portions 33f carried by the governor support. The weights carry adjustable screws 332 adapted to engage the right hand end of the valve member 322; and, upon the attainment of the shaft I88 to effect a reduction in the speedof the rotors, but

not a reductionsuflicient to effect a changed operation of the speed governor permitting the valve 322 again to move to a position for supplying fluid in the manner shown in Fig. 1.7 from the passages 3 l; to the passages 3i 9, since the design of the governor is such that itbecomes operative to force the valve 322 to the left only upon the attainment ofa speed of the order of 7000 R. P. M. while, after once assuming the position of Fig. 19, a falling .off of the speed to a rate of the order of 40303. P. M5is necessary before the Weights will move in and permit the reestablishment of fluid delivery in the manner to effect a change in operation of the. driving gearing. Now, the groove 3E3 is connected at its lower side with a passage 333 which opens through an opening 334, Fig. 15, into the interior of the bore of a valve l2 339 through another peripheral groove 34'! to a space 348 communicating through a passage 349 with the chamber 328.

Within a stepped bore 359, Fig. 26, within the 7 drive shaft 226 there is arranged a hollow plunger 35! which is provided at one end with aper: forated flange 352 adapted to seat against a split ring 353 secured within the inner wall of the drive shaftZZil. The plunger member 35| is en- 'gaged by a spring 359 which reacts against a shoulder 355 within the drive shaft, and a thimble 356 closes the left hand end of the chamber Within which the element 3l is movable. The interior of the chamber communicates through obliquely radially extending passages 35? with the outside of the drive shaft between the ball bearings 222 and 255; and radially obliquely extending passages 358 connect the interior of the stepped bore 353 at the right hand end of the plunger member 35! in communication with the chamber in which the member 219 moves at the right hand side of that member.

The mode of operation of the mechanism described is as follows: When the compressor is started, a driving connection is immediately established between the shaft 226 and the gear 2118, and the pump 2B2 commences to deliver fluid through the passage 295, the bore 2%, the strainer 293, the annular passage 299, the passage 369, the annular groove 363, the passage 334, the chamber 335, the passage 33%, the annular groove 39?, the passages 3H, the groove 325, the passages 3L9, the groove 3l8, the passages 333, 338 and 339, the annular groove 343, the radial passages 342, the chamber 3% and the tube 344, to

the bore 359, where it will pass through the pasreceiving bushing 335 in which there is a rotatable valve 33$.which is adjustable by a handle 33f. This valve, which is primarily used for testing purposes, normally occupies the position shown in Figs. 15 and .16, in which position a 7 diametric passage 338 connects the opening 334 with a passage 339 and with an annular groove 3453 provided in part in a bushing 3M surrounding the right hand end of the shaft i849 and in part in the periphery of that shaft. This annular groove is connected by radial ports 342 with a chamber 3 3 near the right hand end of the shaft I39; and a tube 334 extending axially of the shaft E89 leads to the left hand end of this shaft whereit is centered by a suitable fitting 345.

Before describing the mechanism to which this tube delivers fluid, it may be pointed out that the valve member 322, at speeds of the shaft l88 belowa predetermined number of R. P. M. will be in'the position shown in Figs. '7 and 17, and will connect the pump discharge, via the ports and passages previously described, with the tube 349, but that at peeds above such a predetermined number of R. P. M. the valvemember 322 will assume the position shown in Fig. 19 and cut on communication completely between the pas sagesjll and 3E9 and connect the latter passages, and so the interior of the tube 334, back to the sump through the chamber 328. It may be noted that the valve 336 may be turned at will either to provide a direct and continuous communication between thechamber 385 and the passage 339 through a groove 346 in the valve, or when oppositely turned from central position may eifect a continuous venting of the passage sages in the flange 352 and through the radial passages 358 and bring the clutch discs 262 and 253 into contact with each other. As the oil continues to pass through the tube 344, the member 33I moves to the left, compressing the spring 353, and the compression of this spring is so determined thatthe clutch pressure'will be gradually applied as the member 35f moves to the left. When this member reaches its extreme left hand position, the clutch discs may be firmly pressed against each other, and there will be effected drive of the rotors at the higher speed, with the gear 253 as the driving element. This high speed drive will be continued until the speed of the compressor builds up to such a degree that the valve member 322 will be shifted by the governor and then the slow speed drive between the shaft 229 and the compressor will be initiated.

The control for the valve lZil and for the valve H3 may now be described. The chamber 385 has a laterally extending passage 36l, Fig. 14, communicating with it. The communication of the passage 35! with a passage 362, which extends parallel to but oppositely with respect to the passage 38!, is governed by a spring loaded valve 333. This spring loaded valve operates to maintain a sufficient pressure in the chamber 395 under all ci cumstances when the compressor is running .to insure the operation of the speed change mechanism. Passage 362 opens through a longitudinal slot 364 into an annular chamber 365 surrounding the sleeve 335, and at the oppo site side of said sleeve another longitudinally extending slot 365 connects the annular chamber 335 with a passage 35! which is alined with the passage 382. This last passage has a bore 363 communicating with it, and a valve 369 is reciprocable in this bore and controls a side vent 379 which is connected'with the space 328. The valve stop sleeve 39! 13 36.9 is suitably spring loaded and-serves to resillate-the pressure in the passage 361. Passage 361 communicates through a port 31-! with the bore 3.12 of a valve seat member 373 which is connected by another passage .375 to a passage 316, Fig. 9, leading to a servo-motor 311 which is adapted to close the valve lit, and which passage 376 has 'a branch 316, Fig. 2, which leads to the port 118 for supplying fluid to the cylinder 115 to actuate the piston H4 and shift the position of the valve H3, which'has been heretofore described. The servo-motor 33? comprises a cylinder 380 in which a piston 38! is reciprocable, said piston normally maintained in outer position by a spring 382 and connected by a stem .333 with the valve 120, which is mounted for swinging movement about a pivot mounting 384. It will be understood that if escape of fluid to the sump from the bore 3.12 be prevented, a supply of hy draulio pressure to the servo-motor 3H and :to the cylinder 115 will take :place :sufiicient to cause a movement of thepiston 381 in the cylinder 380 in a manner to close the valve 12c and a movement of the piston I'M in the cylinder H ina manner to actuate the arm ill to the-position shown in Fig, 2 and move the valve M3 to the position shown in Fig. 9. Otherwise, the valve l will remain open and the valve'lls will remain in the position occupied at levels of the aircraft below 20,000 feet. To repeat, if escape of fluid from the bore 312 is interrupted, the valve I20 Will be closed and the histon i3 1 will be moved at once to the. position shown in Fig. 2.

To control the venting of pressure from the bore 3E2 back to the sump, and to maintain a free venting at heights below approximately 20,000 feet, and to interrupt venting sharply when approximately that elevation is attained, the following arrangement has been illustrated. The valve seat member 373 is provided with a plurality .of ports 383, Fig. 2.2,:opening through a surface v38? which provides an annular valve seat 388, and the member 3E3 has, in addition, a central guide extension 339. Slidably mounted upon this extension is a valve element 390. The movement of this valve element in an opening direction is limited by a sleeve portion at! formed on a threaded sleeve member 392 which is supported by a further sleeve mounting element .393 canried by a wall of the housing element 30:1. An adjustable closure element and spring tension regulator 394 engages a spring 355 which acts 14 of the casing 353 are perforated, as at 353%, to perwit the fluid passing from the passages 388 to flow freely back to the-sump through the cham The guide extension 383 is traversed by a pasupon the valve element 320 and normally tends to seat it. Connected to the valve .398 and "to the sleeve member 392 at opposite sides of the sleeve zortion 39-5 are bellows devices 3% and .31??? bounding a chamber 398 in which the sleeve 381i is enclosed, and-this sleeve is perforated so that free communication may at all times. -exist throughout the interior of the chamber 386, The chamber 308 is evacuated, and the comgzression of the spring 3-95 is so determined that until the pressure acting upon the exterior of the -bellows arrangement falls to a predeterminedlow value,

the valve 398 will be held firmly open against the When, however, the pressure the casing 393 falls below a predetermined value, the valve 390 will promptly seat and interrupt the discharge of fluid back to the com and. cause the building up .of such a pressure in the bore .3 62 as to cause the valve to close and the piston H5 to move to the position shown Fig. 2 and shift the several valves which are eon through the same sag-e All? .so that fluid from the bore 3'32 passes from the latter through the passage s52 to the interiors of the sleeve member .392 and the closure member 334. When the valve. tilt-is seated,

fluid supplied under pressure through the pas sage 4E2 acts against the outer end of the valve and counteracts the increase in pressure on the inner end of the valve produced by the fluid acting through the sorts 385.

At lls there is shown a cabin pressure vent valve mechanism controlling the escape of cabin pressure through a vent connection til. The

construction of this valve need not be described.

in this case, but it may be said that it may be of any suitable construction adapted to permit the escape of cabin pressure freely until a predetermined height, such as 8,000 feet, is attained; thereafter to maintain cabin pressure substantiallg constant for another increase in height of the aircraft to 36,090 feet, asmay be desired; an, thereafter to prevent the development of an undesirably high differential between cabin and ambient pressure. A valve suitable for this purpose is disclosed in my copending application Serial No. 468,938,-fi1edl3ecember 14, 1942, now Patent No. 2,484,848, October 18, 1949, and is claimed therein.

When the aircraft is on the ground and ready to takeoff, the supercharger"! 39 Will be operating with the valve 129 open, and accordingly there will be virtually no compression of the air in the first stage thereof except such as may exist by reason of back pressure, and the second stage of the supercharger will be operating single stage because the valve H3 will be in the position opposite that shown in Fig. .9, The air taken from the low pressure stage without compression, as stated, and this air will be delivered to the condu-it 23 and will be distributed by the valve are between the heat exchanger I36 and the space Si automatically by means more fully disclosed in the application of which this present applica tion is a division, namely, Serial No. -4582,4122, filed April 9, 1943., now Patent No. 2,444,951, July 13, 194-8, for Cabin Conditions Controlling Ape paratus, As the valve H3 is at this time. in a position preventing the entrance of air from the space S! to the-second stage ill of the supercharger, the air discharging from the outer course of the heat exchanger 130 will be discharged past the valve 153 and through the con duit [55 to the outside of the aircraft. 15% will be open 'suificiently to accomplish this discharge, for reasons which will shortly be ex p ained. The second stage H? of the supercharger is concurrently taking in air from the inlet it: past the valve H3, whose passage H4- then connects the conduit 83 with the intake i ii of the second stage H! of the supercharger.-

This air after compression will be delivered 08 will be delivered The valve through the conduit [53. The mass flow of in this conduit will be sufficient to cause the valve !58 to be maintained fully open under these conditions. The air discharging. through the conduit I53 will pass through the conduit and past the valve 1&5, 'WhOSfi position at this time will be at right angles to the position shown. in Fig. l, and enter the connection which is a portion of the inner course or the heat ex" changer 133; and the air will then ,use through the heat exchanger 38 and discharge into the cabin through the conduit I 55. A volume of air equal to that which is being continuously supplied through the conduit his will be discharged through the cabin vent valve device did when the aircraft reaches a height oi, 2%,065 feet. The free discharge of the oil pump 5 interrupted by the closureof the valve two things will occur: the valve i2i will be closed and thereafter all air taken into the low oressure stage m3 of the supercharger will be compressed through the number of compressions for which this stage is designed, and, moreover, the oil pressure will be delivered to act upon the piston its and move the valve H3; to interrupt communication of the intake to the h pressure stage H? of the supercharger 89 with he conduit H33 and establish communication between this intake and the conduit E38. Thereafter pressurizing device will operate compound until the aircraft moves below an altitude at which the valve 395, which controls the flow of oil from the oil pump 282, reopens the free escape for the latter. The changes in rate or operation of the supercharger need not be detailed, as they will not affect the general mode of operation of the system but will instead simply cause super"- charger to be operated in the desired It will be observed that the means for loading the low pressure stage is effective to reduce the pressure at which it discharges, but that the mass flow will remain unchanged.

While I have in this application specifically dc scribed one form which my invention may as sumo in practice, it will be understood that this form is shown for purposes of illustration and that the invention may be modified and embodied in various other forms without departing from its spirit or the scope of the appended claims.

What I claim as new and desire to secure by Letters Patent is:

1. In combination, in a supercharger, means forming a pair of intersecting rotor chambers, means forming another pair of intersecting rotor chambers, the chambers of one pair alined. with the chambers of the other pair, helically formed rotors within said first chambers, oppositely helically formed rotors in said second chambers, common shafts for the alined rotors, and means including valve means for selectively connecting the adjacent ends of said rotors in communication with each other, or the remote end of one pair of rotors with the nearer end of the other.

2. in combination, a plural stage rotary cornpressor having an unloading device associated with its first stage and valve means associated with its second stage for selectively connecting the intake of said latter stage with the same source from which the first stage takes flu d or with the discharge of said first stage, and a com-- mon pressure responsive controlling device for said unloading device and for said valve means.

3. In combination, a plural stage rotary compressor having an unloading device associated with its first stage and valve means associated 15 with its second stage for selectively connecting the intake of said latter stage with the same source from which the first stage takes fluid or with the discharge of said first stage, alti responsive means for controlling said unloading device and said valve means.

a. In combination, a plural stage rotary com- -ressor having an unloading device associated with its first stage and valve means associated with its second stage for selectively connecting the intake of said latter stage with the same source from which the first stage takes fluid or with the discharge of said first stage, and altitude responsive means for controlling said run loading device and said valve means for effecting s" astantially simultaneous changes in the operat g positions thereof.

in combination, a plural stage rotary compressor having an unloading device associated with its first stage and valve means associate its second stage for selectively connect g the intake of said latter stage with same source from which the first stage takes-fluid or with the discharge of said first stage, and controlling means for said unloading device and said valve means including hydraulically actuated operating means for each of the same and an altitude controlled device for governing the delivery of a hydraulic operatingfluid to said operating means.

6. In combination, a plural stage rotary cornpressor having an unloading device associated with its first stage and valve means associated with its second stage for selectively connecting the intake of said latter stage with the same source from which the first stage takes fluid or with the discharge of said first stage, and controlling means for said unloading device and said valve means including hydraulically actuated operating means for each of the same and an altitude controlled device for governing the substantially concurrent delivery or a hydraulic operating fluid under pressure to said operating means and its substantially concurrent venting therefrom.

7. In combination, a plural stage rotar cornpressor having an unloading device associated with its first stage and valve means associated with its second stage for selectively connecting the intake of said latter stage with the same source from which the first stage takes fluid or with the discharge of said first stage, and controlling means for said unloading device and said valve means including hydraulically actuated operating means for each of the same and an altitude controlled hydraulic pressure escape controlling device for governing the substantially concurrent delivery of a hydraulic operating fluid to said operating means and its substantially concurrent Venting therefrom.

8. A compound supercharger having a lower pressure stage and a higher pressure stage, each normally compressing the fluid passing through the same, means for connecting the intake of the higher pressure stage to the intake of the lower pressure stage whereby the said high pressure stage becomes a low pressure stage, and means for unloading the low pressure stage effective to reduce the pressure at which it discharges while having its mass flow unchanged.

9. In a multistage supercharger, means for providing for two stages of compression, means for delivering fluid to the first stage and for discharging compressed fluid therefrom, means selectively operative to connect the second stage, with said fluid deliverin means or with the discharge Y 17 means of the first stage, and means for controlling said selective connecting means automatically in accordance with the work demands on the supercharger.

10. In a multistage supercharger, means for providing for two stages of compression, means for supplying fluid to the first stage and for discharging compressed fluid therefrom, an unloading device associated with the first stage, means associated with the second stage for selectively connecting the second stage with the fluid supply means for the first stage or with the discharge means of said first stage, and means for controlling said unloading device and said connecting means for effecting substantiall simultaneous 7 changes in the operating positions thereof, said controlling means being automatically responsive to the work demands on the supercharger.

11. In apparatus of the rotary screw type, a casing, means for dividing the interior of said easing into two longitudinally separated chambers, a male rotor and a female rotor in one of said chambers, another male rotor and another female rotor in the other of said chambers, said rotors in each chamber having intermeshing spiral lobes and grooves cooperating with each other and with the inner surface of the chamber to form working spaces, said casing having for each of said chambers an inlet and an outlet, and valve means for connecting the inlet of one of said chambers with the inlet or with the outlet of the other.

12. In apparatus of the rotary screw type, a casing, means for dividing the interior of said casing into two longitudinally separated chambers, a male rotor and a female rotor in one of said chambers, another male rotor and another female rotor in the other of said chambers, said rotors in each chamber having intermeshing spiral lobes and grooves cooperating with each other and with the inner surface of the chamber to form working spaces, the lobes and grooves on corresponding rotors in the different chambers being of opposite hand, said casing having for each of said chambers an inlet and an outlet, the inlets being closely adjacent said dividing means, and means, including valve means, for connecting the inlet of one of said chambers with the inlet or with the outletof the other.

13. In apparatus of the rotary screw type, a casing, means for dividing the interior of said casing into two longitudinally separated chambers, a male rotor and a female rotor in one of said chambers, another male rotor and another female rotor in the other of said chambers, said rotors in each chamber having intermeshing spiral lobes and grooves cooperating with each other and with the inner surface of the chamber to form working spacesysaid casing having for each of said chambers an inlet and an outlet disposed at the opposite ends thereof and for one of said chambers another outlet between the ends thereof, and valve means for connecting the inlet of the other one of said chambers with the inlet or with the first mentioned outlet of said last mentioned one.

14. In apparatus of the rotary screw type, a casing, means for dividing the interior of said easing into two longitudinally separated chambers, a male rotor and a female rotor in one of said chambers, another male rotor and another female rotor in the other of said chambers, said rotors in each chamber having intermeshing spiral lobes and grooves cooperating with each other and with the inner surface of the chamber to form working spaces, said casing having for each of said chambers an inlet and an outlet disposed at the opposite ends thereof and for one of said chambers another outlet between the ends thereof, and valve devices for connecting the inlet of the other one of said chambers with the inlet or with the first mentioned outlet of said last mentioned one and for controlling said other outlet of said last mentioned chamber.

15. In apparatus of the rotary screw type, a casing, means for dividing the interior of said casing into two longitudinally separated chambers, a male rotor and a female rotor in one of said chambers, another male rotor and another female rotor in the other of said chambers, said rotors in each chamber having intermeshing spiral lobes and grooves cooperating with each other and with the inner surface of the chamber to form working spaces, said casing having for each of said chambers an inlet and an outlet disposed at the opposite ends thereof and for one of said chambers another outlet between the ends thereof, and valve devices for connecting the inlet of the other one of said chambers with the inlet or with the outlet of said last mentioned one and for closing said other outlet when the end outlet of said chamber is connected with the inlet of the other chamber.

WIN W. PAGET.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name I Date 1,508,707 Moss Sept. 16, 1924 1,508,731 Standerwick Sept. 16, 1924 1,523,698 Losel Jan. 20, 1925 1,580,973 Rembold Apr. 13, 1926 1,753,280 Baumann et al. Apr. 8, 1930 2,114,719 Maniscalo Apr. 19, 1938 2,205,793 Hunt June 25, 1940 2,208,428 Nicolet -1 July 16, 1940 2,208,554 Price July 16, 1940 2,246,932 Collins June 24, 1941 2,444,951 Paget July 13, 1948 2,477,003 Paget July 26, 1949 2,484,848 Paget Oct. 18, 1949 FOREIGN PATENTS Number Country Date 2,202 Great Britain 1899 308,445 Great Britain 1929 

